| The restoration of lowland fens in the NetherlandsBackground After the last Ice Age, a series of broad peatlands developed behind the coastal dunes of the western Netherlands. By the end of the 17th century, most of the peat had been excavated for fuel, and a linear pattern of waterlogged trenches and narrow ridges, on which the peat had been piled to dry, was left behind. Many of the ridges were washed away by storms, and the growing bodies of open water eventually developed into lakes. Where the original linear pattern survived, the trenches between the ridges gradually terrstrialised into various fen vegetations, such as quaking bogs, reedbeds, marshes and swamp forests. Traditional reed harvesting and hay-making maintained biodiversity across this range of semi-natural habitats, notably for birds such as bittern Botaurus stellaris, black tern Chlidonias niger, purple heron Ardea purpurea, common tern Sterna hirundo and bluethroat Luscinia svecica.A long process of degradationIn the 20th century however, as agriculture in the surrounding polders became more intensive and productive, farmers left the fens. Natural succession took over and large areas evolved towards uniform, species-poor swamp woodland. The fens began losing their botanical and zoological value. The intensified farming had a second detrimental effect: as the water table in the surrounding polders was lowered to allow higher yields, the fens desiccated and the reed beds acidified. Environmental Conservation- Randstad |  |